Seylon's Tower: former death eaters looking to resurrect Voldemort. Seylon Vane was a wizard who went mad trying to resurrect his daughter who died and built a 15 story tower full of experiments and different kinds of magic to resurrect her.
Primrose Calloway is getting notes from "Harry Potter" (really death eaters) to investigate Seylon's tower. They believe there is a powerful relic hidden there that could bring Voldemort back from the dead.